@AlCosta,
Because i believe in evolution, that life started naturally and evolved through the era way beyond our comprehension of the universe. I believe that life forms can spawn then evolve through the ages wherever it can be possible and not because of divine intervention or a holy god decided it was to be that way.
For instance, why aren't the disonaurs not mentioned in holy books? They inhabited this planet far longer than us. What about the big bang, did a single god created all of this?
I don't believe in miracles either, when men couldn't explain why storms formed over their heads and lightings set on fire forest they had to find out why. What was the sun, the moon, the stars. Religions started like that, because men were asking themselves what were they. Thats my view on it.
Lastly, i understand why people need to have faith in a god, that he is watching over their shoulder. If it is helping them living better that is good for them. I am happy for them. I went through different state, when i was a young boy, i thought there was a god, not necessary a christian, or jew, or muslim, or whatever. I thought there was someone with immense power. Then i grew up, learning why and how. And then, i witnessed death, i learned what was death, and i saw death. Thats when i learned there was nothing after your last breath. At least i believe so.
Every life must end at some point, thats the way it is, why should 'we' human be blessed by the divine creator and graced by a built up just for us, heaven while other life forms can't have it?